Unloading gas barrier face seal

ABSTRACT

This specification discloses a dry running gas seal for gas processing systems in which a rotating shaft enters a high pressure area. The seal comprises a mating ring presenting a seal face and a seal ring providing two concentric seal faces engaging the seal face on the mating ring and cooperating therewith to define a pressure cavity. A chamber for an inert barrier gas is provided in a fixed housing and communicates with a supply of inert gas under pressure. The seal ring has throttling passage between the barrier gas chamber and the pressure cavity. The seal ring is biased towards the mating ring by springs mounted in the housing. These springs provide the loading force under which the seal faces are urged together. Increase in the pressure of the barrier gas is transmitted through the passages to increase the pressure of the gas in the pressure cavity. This increase results in a decrease of the loading forces.

United States Patent FOREIGN PATENTS 1,485,742 5/1967 France PrimaryExaminer-Samuel B. Rothberg Attorney-William Frederick Werner ABSTRACT:This specification discloses a dry running gas seal for gas processingsystems in which a rotating shaft enters a high pressure area. The sealcomprises a mating ring presenting a seal face and a seal ring providingtwo concentric seal faces engaging the seal face on the mating ring andcooperating therewith to define a pressure cavity. A chamber for aninert barrier gas is provided in a fixed housing and communicates with asupply of inert gas under pressure. The seal ring has throttling passagebetween the barrier gas chamber and the pressure cavity. The seal ringis biased towards the mating ring by springs mounted in the housing.These springs provide the loading force under which the seal faces areurged together. Increase in the pressure of the barrier gas istransmitted through the passages to increase the pressure of the gas inthe pressure cavity. This increase results in a decrease of the loadingforces.

[72] Inventor Harold Fredric Greiner Warwick, RJ. [21] Appl. No. 842,203[22] Filed July 16, 1969 [45] Patented Mar. 30, 1971 [73] AssigneeSealol Inc.

Warwick, RJ.

[54] UNLOADING GAS BARRIER FACE SEAL 3 Claims, 1 Drawing Fig.

[52] US. Cl. 277/74, 277/75, 277/s, 277/91 [51] Int. Cl. Fl6j 15/40,F16j 15/54 [50] Field ofSearch 277/3, 27, 74, 75, 91, 83, 85

[56] References Cited UNITED STATES PATENTS 2,679,412 5/1954 Whitfield277/74 2,895,750 7/1959 Gardner et a1.. 277/3 3,347,604 10/1967 Lavelleet a1. 277/71 I8 II 44 14 PATENTEUMARBOIH?! [3572.727

mvsrwon HAROLD F GREINER UNLOADDJG GAS BARRIER FACE SEAL The presentinvention relates to a seal for a rotating shaft which enters apressurized area and which includes a mating ring and a seal ring havingengaging seal faces. The invention is concerned primarily with an inertbarrier gas seal for said faces.

BACKGROUND OF THE INVENTION Where a rotating shaft enters a pressurizedarea through a fixed housing in which it is mounted, it has been thepractice to utilize a seal commonly known as a labyrinth seal. Such aseal is satisfactory where large leakage and reduced efficiency isacceptable. However, where toxic, expensive and hazardous gases arebeing handled, no leakage of the sealed medium is acceptable. Under suchconditions it has been the practice to employ some type of face seal.

A face seal which has met with some acceptance is a liquid barrier faceseal. Such a seal includes, as characteristic elements, a mating ringfixed to a shaft and presenting a seal face normal to the shaft axis. Aseal ring having two concentric seal faces is urged towards the matingring by springs. These faces cooperate with the seal face of the matingring to define a cavity that receives a liquid barrier. This liquid maybe water, oil or any liquid that is compatible with the material beinghandled and which will lubricate the seals.

Such a liquid barrier seal affords certain advantages in that heat isdissipated and the gas being sealed is buffered to prevent leakage.However, it is also accompanied by certain disadvantages in that caremust be exercised in selecting a liquid which is compatible with theoperating conditions. These are the ranges of operating temperatures andthe ability of the process gas being sealed to accommodate slightleakage of the barrier liquid into the gas without adverse effects.

Dry running gas seals have also been proposed; however, known seals ofthis type are subject to unpredictable leakage and are limited to lowpressure in increased proportion to the speed of relative movementbetween the seal faces. This results in short service life and adecrease in dependability.

OBJECTS OF THE INVENTION This invention has, as its primary object, theprovision of a dry running gas seal which obviates the above outlinedunsatisfactory conditions which attend the use of a liquid barrier sealand known dry running face seals.

Another object is to provide a dry running gas seal including a barrierof an inert gas which will not react with, or have any deleteriousaffects on the process gas, should there be slight leakage of thebarrier gas into the process gas.

A further object is to provide, in a face seal of the characteraforesaid, a pressure cavity between a mating ring and a seal ring whichcontains an inert barrier gas and communicates with a source of thebarrier gas under pressure whereby an increase in the pressure of thebarrier gas results in a decrease of the loading forces urging saidmating and seal rings into engagement.

SUMMARY OF THE INVENTION The foregoing objects are attained by the inertbarrier gas face seal of this invention which comprises a mating ringsecured to a rotating shaft and having a sea] face normal to the axis ofthe shaft; a sealing ring biased towards the mating ring by springsgenerating loading forces and having two concentric seal faces engagingthe seal face of the mating ring and cooperating therewith to define apressure cavity; and a barrier gas chamber'communicating with thepressure cavity by throttling passages and which contains an inert gasunder pressure from a supply source. Increase in the pressure of thebarrier gas is effective in the pressure cavity to decrease the loadingforces on the seal faces.

Various other more detailed objects and advantages of the invention suchas arise in connection with carrying out the above noted ideas in apractical embodiment will in part become apparent and in part behereinafter stated as the description of the invention proceeds.

I For a full and more complete understanding of the invention, referencemay be had to the following description and accompanying drawingwherein:

The FIGURE is a longitudinal section through a portion of a shaft, thehousing in which it is mounted, and the inert barrier gas seal of thisinvention.

Referring now to the drawing, a shaft 10 is formed with a shoulder Illhaving a series of sockets 12, an annular groove 13, and a series ofrecesses 14 opening thereonto. A mating ring 15 is fitted over shaft 10with an end face in engagement with shoulder 11. Recesses 16 open ontothis end face and pins 17 in aligned recesses 14 and 16 achieve a loosepositioning of ring 15 on shaft 10. A static seal in the form of O-ring13 is received in groove 13 and is engaged by ring 15.

A retaining ring 19 encircles mating ring 15 and is secured in positionby headed screws 20 anchored in sockets 12. Mating ring 15 is formedwith a skirt 21 which defines a recess receiving a component 22 of amaterial particularly adapted to the conditions of usage. Thus, it maybe of carbon compacted under high pressure. This component 22 of matingring 15 presents a seal face 23 normal to the axis of shaft 10.

A housing 24 is disposed about shaft 10 and is formed with a series ofopenings 25, a duct 26 which communicates with a supply of an inert gasunder pressure, and annular grooves 27 and 28.

A sealing ring carrier 30 is secured in housing 24 by screw bolts 31which pass through openings 25 and are anchored in sockets 32. Staticseals in the .form of O-rings 33 and 34 are positioned in grooves 27 and28 and are engaged by carrier 30 to seal the joinder of carrier 30 tohousing 24.

Carrier 30 has an inner flange 35 the free end of which is spaced fromcomponent 22 of mating ring 15. It also has a longer outer flange 36that extends about mating ring 15 from which it is spaced.

A sealing ring 37 has an intermediate flange 38 extending towardshousing 24 and which rides on flange 35. A dynamic seal in the form ofO-ring 39 received in an annular groove in flange 38 seals thisconnection. Sealing ring 37 has an outer skirt 40 which encircles asealing ring component 41 of the same material as component 22 of matingring 15. An O-ring 42 is an annular groove on the inner surface offlange 36 engages skirt 40 and provides a dynamic seal.

Sealing ring component 41 is formed with concentric flanges 43 and 44which present seal faces normal to the shaft axis and in engagement withsea] face 23. They cooperate with the latter to define a pressure cavity45.

Carrier 30 and its flange 36, together with sealing ring 37 and itsflange 38 define a chamber 46. An opening 47 in flange 36 communicatesbetween duct 26 and chamber 46.

Sealing ring 37 and its component 41 are formed with throttling passages48 which communicate between pressure cavity 45 and chamber 46.

Carrier 30 has an end face 49 which engages housing 24. Opening intothis end face are a plurality of threaded counterbars 50 terminating inrecesses 51. The bottom walls of the latter have openings 52 throughwhich pass expansion springs 53 coiled about stems 54. The inner ends ofthe latter are anchored in the end face of flange 38. Plugs 55 arescrewed into counterbars 50 and close recesses 51.

In describing the operation of the subject gas barrier face seal, it isnoted that any gas such as air, argon, nitrogen or other gas that iscompatible with the process gas is supplied from an appropriate sourcethrough duct 26 and passage 47. This gas is the barrier gas which isunder a pressure in the nature of one atmosphere.

The barrier gas passes from chamber 46 through passages 48 to pressurecavity 45. In this cavity the pressure of the barrier gas tends toseparate components 22 and 41 of the mating and sealing rings. Thus, thepressure of the barrier gas relieves the loading forces of springs 53which urge the faces of flanges 43 and 44 against face 23. It is evidentthat as the pressure of the barrier gas increases the loading forcesdecrease.

While a preferred specific embodiment of the invention is hereinbeforeset forth, it is to be clearly understood that the invention is not tobe limited to the exact constructions, mechanisms, and materialsillustrated and described because various modifications of these detailsmay be provided in putting the invention into practice.

lclaim:

1. In an unloading gas barrier face seal designed for use with a shaftrotatably mounted in a housing and entering an area of pressurized gas:

a. a mating ring secured to the shaft and having a seal face normal tothe axis of said shaft:

b. a carrier in said housing having an annular flange:

c. a sealing ring axially movable in said carrier and having an annularflange engaging said flange on said carrier, said sealing ring beingmovable relative to said mating ring, said housing and sealing ringcooperating to define a chamber;

d. a passage in said housing for introducing an inert barrier gas underpressure into said chamber;

e. a pair of spaced concentric flanges on said sealing ring presentingseal faces engaging the seal face of the mating ring and cooperatingtherewith to define a pressure cavity between said mating and sealingrings:

f. a throttling passage in said sealing ring communicating between saidchamber and said pressure cavity; and

g. spring means mounted in said carrier and effective on said sealingring to urge said sealing ring towards said mating ring where loadingforces on said engaging seal faces are generated, said loading forcesbeing opposed by the pressure of the barrier gas in the pressure cavity.

2. The unloading gas barrier face seal of claim 1 in which the springmeans comprises a plurality of angularly spaced expansion coil springsmounted in the carrier and engaging the sealing ring.

3. The unloading gas barrier face seal of claim 1 in which the carrierhas an outer annular flange spaced from the flange on the sealing ringand cooperating therewith to define the chamber.

1. In an unloading gas barrier face seal designed for use with a shaftrotatably mounted in a housing and entering an area of pressurized gas:a. a mating ring secured to the shaft and having a seal face normal tothe axis of said shaft: b. a carrier in said housing having an annularflange: c. a sealing ring axially movable in said carrier and having anannular flange engaging said flange on said carrier, said sealing ringbeing movable relative to said mating ring, said housing and sealingring cooperating to define a chamber; d. a passage in said housing forintroducing an inert barrier gas under pressure into said chamber; e. apair of spaced concentric flanges on said sealing ring presenting sealfaces engaging the seal face of the mating ring and cooperatingtherewith to define a pressure cavity between said mating and sealingrings: f. a throttling passage in said sealing ring communicatingbetween said chamber and said pressure cavity; and g. spring meansmounted in said carrier and effective on said sealing ring to urge saidsealing ring towards said mating ring where loading forces on saidengaging seal faces are generated, said loading forces being opposed bythe pressure of the barrier gas in the pressure cavity.
 2. The unloadinggas barrier face seal of claim 1 in which the spring means comprises aplurality of angularly spaced expansion coil springs mounted in thecarrier and engaging the sealing ring.
 3. The unloading gas barrier faceseal of claim 1 in which the carrier has an outer annular flange spacedfrom the flange on the sealing ring and cooperating therewith to definethe chamber.